Dietary Calcium May Prevent Spread of Breast Cancer to the Bone

A strong skeleton is less likely to be penetrated by metastasizing cancer cells, therefore, a fortified glass of milk might be the way to block cancer's metastasis, according to researchers.

Using a mouse model of breast cancer metastasis, researchers from the ANZAC Research Institute (Concord, Australia) discovered that a calcium deficiency may increase the tendency of advanced breast cancer to target bone. Dietary calcium, they theorize, might help prevent the spread of breast cancer to bone and serve as an adjuvant treatment during therapy.

The study's findings were presented in the October 1, 2007, issue of the journal Cancer Research. According to the researchers, approximately 70% of patients who develop advanced breast cancer will have secondary tumors in the bone. The spread of cancer to bones leads to cellular processes that physically break down existing bone, leading to further pain and illness. In fact, the breakdown of bone and subsequent bone re-growth forms what senior author Colin R. Dunstan, Ph.D., terms a "vicious cycle” that turns bone into an environment conducive to cancer growth.

To better determine the role of bone turnover in the spread of cancer, Dr. Dunstan and his colleagues compared the effects of a low- and high-calcium diet in mice. They found that dietary calcium deficiency--independent of the biochemical factors that control turnover--was related to a considerably higher increase in cancer cell proliferation and the total proportion of bone that had been penetrated.

"These results could have implications for patients with breast cancer bone metastases or who are at high risk for developing metastatic disease,” Dr. Dunstan remarked. "Many older women in our community are known to be calcium-deficient due to low calcium dietary intake or due to vitamin D deficiency. These women could be at increased risk for the devastating effects of bone metastases.”

According to Dr. Dunstan, these findings call for additional, directed clinical trials "to investigate how calcium and vitamin D status influence progression to metastatic disease, and to determine if corrections of calcium and vitamin D deficiencies are important in breast cancer patients.”


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ANZAC Research Institute